11 October 2023, 21:33 | #1 |
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A4000 Help - Black Screen
Hi Folks,
A4000d. Without ChipRam gets as far as a green screen. Pwr LED dull, then bright. Diagrom Sluggishly displays over serial - first line of text/ credits - but quickly starts to write 010101 etc With ChipRam black screen that eventually goes dark purple. No output to serial diagrom with the exception of a few blocks of random ascii. Im stumped. Anyone seen this before? |
11 October 2023, 22:01 | #2 | |
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Quote:
Have you removed the Varta battery? Sounds like you got some burned traces on your mobo. |
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11 October 2023, 22:05 | #3 |
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Yes, recapped, battery removed, traces repaired, Ricoh removed....
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11 October 2023, 22:13 | #4 |
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haha yes indeed - and Im sure he would have it fixed in a jiffy!. Problem is, well, I have a problem with problems - and its sat there languishing on my workbench, laughing at me everytime I go in there and, frankly, annoying me. alot. lol. arrrgh.
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12 October 2023, 00:32 | #5 |
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So - I buzzed out the Chip Ram socket when I replaced it - it did need a bodge wire but everything else checked out ok.
The PSU is original - giving me a good voltages. I did, out of interest, try a new PSU just on the off chance - made no difference. |
12 October 2023, 00:53 | #6 |
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I guess really, ive been looking at trying to understand the route to the chip ram - CPU is working, Kickstart is ok I guess - Chipram socket is populated - dodgy Brigette? - U212? not sure where to look next or even what to scope.
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25 October 2023, 10:08 | #7 |
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Hi - I've just had some fun restoring an A4000 rev B too so just wanted to try and help if I can (I'm no expert!).
Did you say you replaced the chip ram socket and checked continuity for all the socket connections up and under the board? I ask as I had a via damaged by cap juice near C200 and the via's under U852 can get hit by battery juice. Amiga PCB explorer is a fantastic resource to help check all these traces, if you haven't used it already. Obvious stuff; - J213 set to 2mb? - INT/EXT jumpers correct (I would guess so, as you had a green screen)? - Tried a different ram stick - I still get 2mb shown with a 2 or 8mb stick, FPM or EDO works for me. I've read that 2,8,32mb sticks are electrically 'double sided' even if the chips are only on one side. - Used contact cleaner on the socket (in case any flux went wandering)? Last edited by Screechstar; 25 October 2023 at 10:13. Reason: formatting & extra question |
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